The network-resources needed to deliver a service are constrained by the interconnecting technologies that make up the network. Due to business reasons, the capacity of the service provider's network cannot grow linearly with the addition of new end users. As a result, the service provider must perform what is referred to as oversubscription. This means the same resources in the network are sold multiple times to different end users.
Oversubscription is based on the principle that not all users will be consuming their data pipe simultaneously. The service provider estimates how much simultaneous usage there will be of the network and provides some maximum limits to the amount of resources used by each data pipe. During times of congestion (i.e., many end users trying to access the network at the same time with traffic levels exceeding what the network can handle) the quality of service associated with the sessions may degrade substantially if the network cannot differentiate between those sessions that require special treatment and others that do not require such special treatment. This results in the resources consumed by a service (or an aggregate of services) being limited by the characteristics of the data pipe to the end user.
For example, in a video-on-demand application (e.g., where a user requests a video clip or movie) if an end user wishes to download streaming video from a content provider (i.e., a dynamic service) via today's static data pipe the viewing experience would likely be much poorer than the viewing experience one would get by watching traditional broadcast TV. The reason for this is that there is a certain amount of bandwidth that is needed for the video frames to be delivered which if not made available by the network, results in poor viewing quality (e.g. jerky, frame loss, etc.) for the user. This is true if the service provider access network is based on best effort delivery of content, which can be inadequate compared to the quality of service needed for such service delivery. This is especially true in a shared contention based access network where multiple users contend for the same set of network resources.
Today, the model often used for offering differentiated services to the end user is Tiered Services (e.g., bronze, silver, gold). Service providers offer a tiered service model in which the characteristics of the data pipe may differ based on the tier that the end user or subscriber has subscribed to.
One approach that has been proposed for delivering services that are more responsive to changing network conditions and that is designed to permit distinguishing among the levels of quality of service provided to various subscribers and providers is described in U.S. Ser. No. 10/867,157, filed Jun. 14, 2004, entitled “Dynamic Service Delivery Platform for Communication Networks,” incorporated herein by reference. According to that approach, the policy server stores rules or policies regarding the level of service that various subscribers are entitled to receive from various providers and then to allocate resources in accordance with those policies.
It discloses a method of managing dynamic services that are provided over a network. The method involves: storing rules for controlling admission to the network; keeping track of state of the network; receiving a request for establishing a session over the network; and using both the stored rules and the state of the network to determine whether to grant the request for establishing the session.